> And what is the cost of unplugging devices after every use?
You really think your time is worth so much that taking 10 seconds extra for plugging/unplugging a device is worth even considering?
> Not just replacing sockets or cables
Never happened to me once in over 3 decades. Both sockets and cables usually have a longer lifespan than any of your appliances.
> Are electronic components happy now with the constant power on/off cycles?
Depends entirely on the design of the device and the components used.
The notion stems from the olden days of analogue devices, which indeed often didn't like being power cycled. Turning appliances on and off twice a day, though, doesn't affect the lifespan in the slightest.
Unless you're using something with tubes in it, there is basically no penalty to unplugging. I use a power strip with a switch so I have the option to turn off everything when I want to.
If you use 5 devices a day and need 30 seconds for plugging and unplugging, this will accumulate to 75 hours per year. If you make 15€ per hour, the cost of opportunity would be 1140€. Ouch!
Not just replacing sockets or cables, but is not true that (electronic) devices have a longer live if they are always plugged in?
Are electronic components happy now with the constant power on/off cycles?